Tunable nanopillar array on a quartz-fiber tip for surface enhanced Raman scattering (SERS) detection

In this work, a simple two-step method to create tunable self-assembled three-dimensional nanostructure array-like nanoantennas directly on the tip of an optical quartz glass fiber is described. The structures are prepared by using dry etching of the fiber tip. For the etching process, gold nanoparticles fabricated by thermal dewetting technique were used as template. The structures are applied as sensors for label-free analysis of organic substances in ppb range, such as drug residues in liquid solutions. The measurements are carried out by a portable Raman device with an exchangeable sensor head utilizing the SERS-effect. This method allows in situ applications. In order to characterize the SERS cells, para-thiocresol and diclofenac sodium are used as model substances. For optimization of the substrate performance, different thicknesses of the dewetting-layer (6, 9, 12 nm), different etching times for formation of the pillars (6, 8, 10 and 12 min), and different thicknesses of SERS-metallization (25, 50, 75 nm) of gold and silver are compared. In order to show the applicability of the structure on the tip of a fiber, measurements from the upper side and from the underside of the substrate on quartz plates are compared. Reproducible SERS enhancement factors up to 10 7 {10^{7}} were achieved.

Analysis of the Test Method of Quartz Glass Optical Homogeneity

The optical quartz glass is widely applied in optical system , photo communications，inertial navigation，etc.It must have high optical homogeneity. Optical homogeneity of the optical quartz glass directly affects the wavefront quality of the optical transmission system, and changes the wavefront aberration of the system. How to accurately determine the optical homogeneity of the quartz glass is especially important. Currently，the method of test for optical homogeneity mainly used by interference principle. This paper analyzes various existing interference measurement method and test equipment. Summarized the advantages and disadvantages of various test methods，using range and measurement accuracy.